1. Field of the Invention
This invention pertains generally to profile sanding devices, and more particularly to an improved sanding wheel for use with a rotary disk sanding apparatus such as those disclosed in U.S. Pat. No. 4,744,180, issued May 17, 1988, to Theodore Voorhees; and U.S. Pat. No. 4,870,787, issued Oct. 3, 1989, to Theodore Voorhees; owned by the inventor. These patents are incorporated by reference herein as though set forth in full. The patents describe a cylindrical sanding wheel with abrasive operably coupled to a motor and guide and configured to sand the edge of a generally planar workpiece.
2. Description of Related Art
Motorized tools with distinctively shaped blades have been used to shape or contour the edges of wooden workpieces for use in door center panels and edges, bar and chair rails, casing, wainscots, crown moulding, window sills and the like. Such tools provide a consistent and precisely shaped edge on a plank that is far superior to what can be achieved by hand. However, in either case, the contoured edges typically require sanding in order to remove any irregularities due to the grain of the wood, knots or other imperfections and to prepare the contoured workpiece for staining or painting.
Sanding an angled edge with sandpaper by hand can produce rounded edges or grooves because of inconsistent pressure and imprecise placement of the abrasive paper. Sanding by hand is also inefficient and incompatible with large scale milling operations.
Grinding disks and sanding wheels were developed to provide consistency in the sanded surface and overall contour. Sanding wheels are typically mounted axially to a motor driven shaft. The head of the wheel has a contoured shape that engages and abrades the milled edges of the panel. The sanding wheel may be drawn across the edge of the panel or the panel drawn across the sanding wheel. Sanding belts have also been used with simple contours.
One difficulty experienced with the use of sanding disks and belts is the build up of dust on the abrasive surfaces that reduce the function of affected points on the abrasive surface and limits the useful life of the sanding disk. It is often necessary to make multiple passes over the sanding heads due to the dust build up on the abrasive surface of the belt or disk. Sections of the sanding wheel that are configured for sanding small or tight edges in the contour of a workpiece are particularly susceptible to dust buildup. Inconsistent wear or dust clogged abrasive surfaces can result in scarring of the surface of the workpiece as well as rounded corners or inside edges of the profile.
Another difficulty experienced by the sanding heads of the prior art is the imprecision found in the sanding head and sanding operation. Imprecise sanding operations can result in dulled or inconsistent edges and notches. Even with custom made sanding wheels, it is difficult to form the abrasive on the sanding wheel to match a convex sharp contour because the plane of the abrasive must form as a radius equal to the material thickness to provide a sharp edge while sanding. Consequently, multiple passes in machines with different wheels configured for different portions of the panel profile are required to cut and maintain a sharp linear edge or notch in the workpiece.
It can be seen that the need for multiple sanding wheels in several machines and several passes through the machines is both time consuming and expensive. In addition, the abrasive on the edges of the sharp corners of the sanding wheel profile experiences greater wear than the abrasive near the center of the strip greatly reducing the service life of the sanding wheel.
Replacement or repair of the sanding wheel will require the line of operations to stop to allow the wheel to be changed resulting in a loss of production time and increased expense. This productivity loss is compounded when the number of sanding wheels and sanding machines in the processing line is increased.
Accordingly, there is a need for a sanding wheel with multiple cutting edges that is resistant to the build up of abrasive dust and that will have a horizontal and vertical profile that can maintain sharp edges and grooves as well as arcuate surfaces of a workpiece. The present invention satisfies that need as well as others and generally overcomes the deficiencies in the art.